Shock therapy device



July 15, 1958 H. J. OYSTON ETAL SHOCK THERAPY DEVICE Filed Feb. 24, 1955 HARvLD AMEs OYSTON ARREN scams LUHB ATTORA/EI INVENTORS I SHWCK THERAPY DEVICE Harold .larnes Oyston, North Strathfield, near Sydney, New South Wales, and Warren George Lumh, Summer lllill, near Sydney, New South Wales, Australia, assrgnors to Amalgamated Wireless (Australasia) Limited, Sydney, Australia, a company of New South Wales Application February 24, 1955, Serial No. 490,344 (Ilairns priority, application Australia April 12, 19%

3 Claims. (Cl. 128-419) The present invention relates to a medical shock machine and more particularly to a shock machine for use in electric shock therapy.

Electric shock thereapy is used in the treatment of certain mental disorders. Shock voltages ranging from 75 to 150 volts from an A. C. supply source are applied to the patients head through suitably placed electrodes for very short periods of time.

The shock periods are usually of from 0.1 to 0.5 second duration. The period within these limits, which is most suitable for the patient undergoing the treatment is selected by the physician and it is most important that the time period specified is not exceeded.

When the shock voltage is applied the patient is usually seized with a violent convulsion followed by unconsciousness; certain curative effects frequently follow the proper employment of this shock therapy.

It is, however, very essential for the safety of the patient to ensure that no condition is likely to arise in the operation of the apparatus, such as would expose the patient to a shock of excessive time duration.

An important requirement therefore in apparatus of this nature is that failure of a component should, as far as possible, result in total inoperation rather than wrong operation of the system.

An automatic timing system'with an adjustable timing 7 circuit should be included in the system to control the time duration of the shock period. The nature of the timing system should be such that it will function to open the patient circuit at the expiration of the required time period, even though the switch which controls the applica tion of the shock voltages to the patient is still maintained in the operative position.

Various timing arrangements, both mechanical and electronic have been suggested in the past, but all of these prior art timing systems have suffered from disadvantages which have seriously restricted the scope of their usefulness.

One of the objects of the present invention is to provide a medical shock machine which il1Cl11d6S an improved automatic timing system which will provide a greater degree of safety for the patient than any of the timing systems previously suggested.

When subjecting a patient to electric shock therapy it has now been found that the sudden application of the shock voltage in accordance with conventional pracitce is undesirable and is likely also to endanger the safety of the patient.

Accordingly it is a further object of the present invention to provide a medical shock machine in which the shock voltage is not applied suddenly, but requires a predetermined time to build up to its peak value after the energization of the system.

A still further object of the present invention is to provide a medical shock machine in which the disadvantages associated with prior art apparatus of the same general type are greatly reduced or eliminated and which op- 2,843,129 Patented July 15, 1958 ice if: erates automatically to provide the greatest possible protection for the patient.

The above objects are achieved by providing, in ac-- co-rdance with the present invention, an improved medi cal shock machine comprising in combination means for applying a shock voltage of alternating polarity within a predetermined voltage range to a patient requiring treatment, means including a temperature dependent resistor having a negative temperature coefiicient for controlling the time period that the applied voltage takes to build up to its full value, and an electronic automatic timing circuit for accurately timing the duration of the shock period, said timing circuit including a thermionically controlled relay which operates to control the circuit through which the shock voltages are applied to the patient and which is maintained in the inoperative position when said first mentioned means is de-energized.

For a more complete understanding of the invention and the manner in which it is to be carried out, attention is now directed to the following description in connection with the accompanying drawing in which- Figure 1 illustrates one practical circuit arrangement embodying the present invention.

Referring to the drawing, A. C. potentials derived from terminals 1., 2 which are connected to an A. C. supply source (not shown) are applied to a pair of electrodes 3, 4 through a step down transformer 5.

The step down transformer 5 has a primary winding 6 and a secondary winding 7. The primary winding 6 is connected at one end to the terminal 2 of the A. C. supply source. The other end of the primary winding 6 is connected through a switch 8, the particular temperature dependent resistor 9 to 14 which is selected by a switch 15, and the cooperating contacts of the switch 15 to the other terminal 1 of the A. C. supply source.

In the drawing the switch 8 is shown in the oil condition which is the normal or inoperative position for this switch.

One end of the secondary winding 7 of the transformer 5 is connected through a switch 16 to the electrode 4. The high potential end of the secondary winding 7 is provided with a number of tapping points 17 to 23 to enable a range of voltages to be selected by the switch 24 and applied to the electrode 3 through a switch 25.

The points 1'7 to 23 are provided on the secondary winding 7 to provide a range of voltages varying in the desired steps between and volts. Although in the present example only 7 tapping points are shown on the winding 7, it is to be understood that a greater or lesser number of taps may be used if desired, depending on the voltage increments required between steps. The temperature dependent resistors 9 to 14 are of the conventional self-heating type in which variations in the effective amplitude of the current passing through them give rise to marked changes in their temperature and resistance. In the present example the resistors 9 to 14 have a negative temperature coeflicient of resistance, i. e. as the current through them increases their resistance value decreases. Resistors of this type are generally referred to in the art as thermistors. As the temperature of a thermistor takes a short time to return to normal after current passes through it, it is advisable, if a number of operations are to be carried out without a short period, to employ a number of resistor elements which can be selected individually by the switch 15. The switch 15 is operated to select a resistor element whose temperature is normal at the commencement of each operation. The operation of the switch 15 may be effected manually or it may be arranged in any convenient manner to automatically select a fresh resistor each time the apparatus is energized to carry out an operation.

The improved timing circuit employed in the present invention is enclosed within the dotted rectangle 26. A thermionic valve 27 has its anode 28 connected to the positive terminal 29 of the D. C. potential supply source 30 through the energizing winding of a relay 31. The cathode 32 of the valve 27 is connected to ground 33 and the negative terminal 34 of the potential supply source 3th is connected to ground 33 through a cathode resistor 35. The cathode 32 of the valve 27 is also connected to the positive terminal 29 of the potential supply source 30 through a resistor 36. The resistors 35, 36 thus provide a potential divider network across the output terminals 29, 34 of the potential supply source 30. With this potential divider connection the cathode 32 is maintained at a fixed positive potential with respect to ground during operation of the apparatus.

The resistor is provided with a variable tap 37. The tap 37 is a moving contact, the contact position of which may be varied along the whole or part of the length of the resistor 35 to provide a range of biassing potentials for the grid 38 of the valve 27.

Biassing potentials from the resistor 35 are applied to the grid 38 through the tap 37, the grid resistor 39 and the grid stabilizing resistor 41?.

The timing capacitor 41 is connected between the tap 37 and the moving arm 43 of a 2-way switch 42.

In one position of the switch 42 the capacitor 41 is connected to a charging circuit consisting of the resistors 44-, 45 connected as a potential divider across the output terminals 29, 34 of the supply source 30. In the present 7 example the capacitor 41 is connected through the switch 42 to the junction point 46 of the resistors 44, 45. As this is the normal or inoperative position of the arm 43 of the switch 42, the capacitor will become fully charged whenever the apparatus is connected to the A. C. supply source (not shown) by operation of the mains switch 47.

The moving arms of the switches 8 and 42 are ganged together for simultaneous operation as indicated in the drawing by the dotted coupling link. In the present example the ganged switches are moved to their operative position by means of a spring loaded push button 4-8. The nature of the arrangement is such that when the push button 48 is released the switch arms of the switches 8, 42 are automatically restored to their normal or inoperative positions.

Any convenient source of D. C. potential, such as for example a battery or a. conventional A. C. mains rectifying circuit capable of supplying the required D. C. operating potentials to the terminals 29, 34 may be used as the D. C. potential supply source generally indicated by the rectangle 30.

In the present example an A. C. mains rectifying system connected to the A. C. supply terminals 1, 2 is used to provide the required D. C. potentials across the terminals 29, 34-. As the circuit arrangement and operation of an A. C. mains rectifying system is well understood, a detailed description is considered unnecessary.

Heating potentials for the cathode 32 of the valve 27 may be derived and applied in any convenient manner.

The relay 31 employed in the timing circuit 26 is utilized to control the operation of switches 16, 25 in the energizing circuit for the electrodes 3 and 4. When the relay 31 is energized the switches 16, 25 are closed and when the relay 31 is de-energized the switches 16, 25 are open.

The operation of the apparatus is as follows: Closure of the main switch 47 energizes the potential supply source 30, which provides D. C. operating potentials for the valve 27 in the timing circuit 26. When the switch 42 is in its normal position as shown in the drawing, the capacitor 41 is immediately charged to a voltage which is determined by the potential difference between terminals 29, 34 and the resistance ratios of the resistors 44, 45 less the voltage developed between the tap 37 and ground 33.

iii

The position of the tap 37 is adjusted along the resistor 35 until the biassing potential applied to the grid 38 is sufficient to cut off the anode current through the valve 27 or to reduce the anode current to a value less than that required to energize the operating winding of the relay 31.

The output switch 24 is then adjusted to select from the voltage range available the voltage that has been prescribed by the physician for application to the patient undergoing treatment. The contact electrodes are placed on the patients head in a position such as will enable the applied voltage to cause a current to flow through the afiected part, and the push button contact 48 pressed to simultaneously actuate switches 8, 4-2 to the operating position.

Operation of switch 8 closes the primary circuit of the transformer 5 and allows current to flow through the primary winding 6 and the thermistor element previously selected by the switch 15. The simultaneous operation of the switch 42 disconnects the capacitor 41 from the charging circuit and connects it to the grid 38 of valve 27. The high positive potential charge on the capacitor 41 cancels the static negative potential applied to the grid 38 from the tap 37 and causes the valve 27 to conduct. The increased anode current through valve 27 and the energizing winding of the relay 31 causes the relay 31 to operateand close the switches 25, 16 in the circuit which energizes the electrodes 3 and 4.

When the switches 25, 16 are closed, the output voltage is applied to the patient through electrodes 3 and 4. The voltage is not applied suddenly as has been the practice in the past. Due to the presence of the thermistor element in the primary circuit the output voltage increases steadily and smoothly to its full value. As the current flows through the primary winding 6 and the selected thermistor element, the temperature of the thermistor element increases and its resistance decreases with consequent increase in primary current and output voltage until the thermistor element stabilizes.

The length of time during which current will continue to flow in the output circuit of the transformer 5 is governed by two things: firstly, the length of time that the push button is depressed to maintain the ganged switches 8 and 42 in the operative position; and secondly, the time taken by the charge on the capacitor 41 to discharge through the resistor 39 to a value such as will allow the current through the valve to fall to a value less than that required to maintain the relay 31 in the operative condition.

It will be seen from the drawing that if the push button is released before the expiration of the time period fixed by the timing circuit 26, that is, before the capacitor 41 has discharged sufficiently to cause de-energization of the relay 31, the switch 8 will be opened and current will cease to flow in the output. 7

If on the other hand the push button is held depressed longer than the required time, the output circuit will be broken by theo-pening of switches 25, 16 when the relay 31 is de-energized by the operation of the timingcircuit 26.

The time duration of the shock period may be readily controlled by adjusting the position of the tap 37 on the cathode resistor 35.

Adjusting the position of the tap 37 on the resistor 35 controls the amplitude of the effective potential developed across the capacitor 41. The higher the value of this potential the longer the time required for the capacitor to discharge through the resistor 39 to a value such as will cause de-energization of the relay 31.

In actual practice, moving the tap 37 towards the cathode end of resistor 35 increases the duration of the shock period and moving the tap 37 towards the earth end of the resistor 35 reduces the duration of the shock period.

Due to the presence of the thermistor element in the circuit, shock periods of longer duration than those specified for prior art apparatus employed for similar purposes are required. This is due to the fact that the output voltage is not applied suddenly with possible danger to the safety of the patient as in the past, but is caused by the action of the thermistor to increase steadily and smoothly to its peak value.

In order to compensate for the time taken by the output voltage to build up to its peak value, the time constants of the timing circuit 26 should be adjusted to provide shock periods of from 0.5 to 1.5 seconds.

In medical shock machines constructed in accordance with the improved circuit of the present invention, the element of risk so far as the safety of the patient is concerned, is considerably reduced in comparison with apparatus previously employed for similar purposes.

As the arrangement of the timing circuit in the improved medical shock machine of the present invention is such that the relay 31 is inoperative in the normal condition of the apparatus, failure of the valve or circuit components during operation will automatically cause the relay 31 to be restored to its normal or inoperative condition, thus opening the contacts 25, 16 in the output circuit. Furthermore, the danger of the relay contacts sticking, due to polarization, which has occurred in prior art apparatus where the relay has been operative in the normal condition, has been reduced to a remote possibility. Even this possibility is counteracted to some extent by push button control of the ganged switches 42, 8. The release of the push button 48 at the expiration of the estimated time period prevents current flow in the output circuit even if by some remote chance the relay 31 remains operated beyond the specified period. As the shock periods employed in the present apparatus due to the presence of the thermistor element in the circuit are from 0.5 to 1.5 seconds instead of 0.1 to 0.5 as employed in previous apparatus, it is possible to estimate the required time period sufl'iciently accurately to avoid shock periods of excessive time duration.

We claim:

1. A shock therapy device comprising an alternating current transformer having primary and secondary windings, a pair of applicator electrodes connected to the secondary winding of said transformer, alternating potential input means, a rectifier connected to said input means, connecting means between said input means and said transformer for applying alternating potentials from said input means to the primary winding of said transformer, said connecting means including one of a plurality of thermistors, a power control switch for energizing said shock therapy device and a multi-position selector switch for individually selecting and including said thermistors in said connecting means, automatic electronic timing means connected to said rectifier and including a thermionically controlled relay having contacts in circuit between said secondary winding and said applicator electrodes for controlling the application of shock voltages from said secondary winding to said applicator electrodes, said timing means including a timing capacitor arranged to control the operating time of said thermionically controlled relay, said timing means also including a thermionic valve having a resistor in its cathode circuit, an adjustable tap connected to said resistor, said timing capacitor having one terminal connected to said adjustable tap, and a selector switch connected to the other terminal of said capacitor and adapted to connect said timing capacitor alternatively to said rectifier and to the grid circuit of said thermionic valve.

2. A shock therapy device as set forth in claim 1 wherein said power control switch and said selector switch for said timing capacitor are mechanically linked for simultaneous operation.

3. A shock therapy device comprising an alternating current transformer having primary and secondary windings, a pair of applicator electrodes, one of said electrodes being connected to the low potential end of said secondary winding through a first relay control switch and the other of said electrodes being connected to one of a plurality of tapping points at the high potential end of said secondary winding through a second relay control switch, a manually operated voltage control switch for selecting one of said tapping points, alternating potential input means, connecting means between said input means and said transformer for applying alternating potentials to the primary winding of said transformer, said connecting means including a power control switch for energizing said shock therapy device and one of a plurality of thermistors, a manually operated multi-position selector switch for individually selecting and including said thermistors in said connecting means, said connecting means including an automatic electronic timing means having a thermionically controlled relay wherein energization of said relay closes said relay control switches in the connections between said applicator electrodes and said secondary winding, a timing capacitor arranged to control the operating time of said thermionically controlled relay, said timing capacitor being connected between an adjustable tap on a resistor in the cathode circuit of a thermionic device controlling operation of said relay and a selector switch adapted to connect said liming capacitor alternatively to a source of charging potential of unidirectional polarity or in parallel with the grid resistor of said thermionic device, said power control switch and said selector switch for said timing capacitor being mechanically linked for simultaneous operation, and a spring loaded push button arranged to operate simultaneously said two last mentioned switches.

References Cited in the file of this patent UNITED STATES PATENTS 1,667,451 Arnberg Apr. 24, 1928 2,028,338 Le Bel Jan. 21, 1936 2,099,511 Caesar Nov. 16, 1937 2,190,282 Browner Feb. 13, 1940 2,295,585 Lindquist Sept. 15, 1942 2,438,875 Ofiner Mar. 30, 1948 FOREIGN PATENTS 839,556 France Jan. 4, 1939 

